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Shorebirds, or waders, form an ecologically (but not phylogenetically) homogenous group of birds that, despite this homogeneity, exhibits clear correlated contrasts in habitat use and migration distance between closely related species pairs. In addition, within species there is distinct variation in breeding and wintering latitudes, i.e. migration distance. I examine here such contrasts at different taxonomic levels and evaluate what we can learn about selective forces on habitat selection and the evolution of migration strategies in birds. My primary example is the worldwide migration system of the Red Knot Calidris canutus. These sandpipers breed only on high arctic tundra (65-83 degrees N), but they move south from their disjunct, circumpolar breeding areas to nonbreeding sites on the coasts of all continents (except Antarctica), between latitudes 58 degrees N and 53 degrees S. Due to their specialized sensory capabilities, Red Knots generally eat hard-shelled prey found on intertidal, mostly soft, substrates. As a consequence, ecologically suitable coastal sites are few and far between, so they must routinely undertake flights of many thousands of kilometres. In contrast to prediction, Red Knots at tropical intertidal sites have lower fuelling rates than birds at more southern or northern latitudes. This leads to greater time-stress in the southernmost wintering populations that not only have to cover over 14,000 km in single migrations, but also cannot rely on tropical regions to make refuelling stops. Rapid human-caused losses of the food-base in staging areas during both north- and southward migrations have been demonstrated to have caused rapid declines in several Red Knot populations. Detailed worldwide ecodemographic research on these extreme long-distance migrants, as embodied in, for example, the recently established Global Flyway Network, yields a two-pronged benefit: (1) on the basis of the unintended large-scale experiments carried out by humans, we rapidly come to grips with the selection pressures moulding the migration strategies of migrant birds, and (2) in applied contexts, the work gives instantaneous feedbacks on the conservation consequences of man-made alterations to wetland environments at the relevant global spatial scales.

Historic Christmas Bird Count and eBird data indicate that during winter invasions, North American irruptive fringillid species occur in relatively even numbers across latitudes east of the Rocky Mountains. Most boreal breeding species show large southward invasions every other winter, with this pattern typically being strongest across the northern and mid United States. eBird data confirms that many northern fringillids irrupt synchronously, and both datasets also show positive correlations between the winter movements of southern breeding species in many areas. Winter abundance records show negative correlations between northern breeding species and southern breeding species in nearly all monitored areas of North America.

Background Identifying movement routes and stopover sites is necessary for developing effective management and conservation strategies for migratory animals. In the case of migratory birds, a collection of migration routes, known as a flyway, is often hundreds to thousands of kilometers long and can extend across political boundaries. Flyways encompass the entire geographic range between the breeding and non-breeding areas of a population, species, or a group of species, and they provide spatial frameworks for management and conservation across international borders. Existing flyway maps are largely qualitative accounts based on band returns and survey data rather than observed movement routes. In this study, we use satellite and GPS telemetry data and dynamic Brownian bridge movement models to build upon existing maps and describe waterfowl space use probabilistically in the Central Asian and East Asian-Australasian Flyways. Results Our approach provided new information on migratory routes that was not easily attainable with existing methods to describe flyways. Utilization distributions from dynamic Brownian bridge movement models identified key staging and stopover sites, migration corridors and general flyway outlines in the Central Asian and East Asian-Australasian Flyways. A map of space use from ruddy shelducks depicted two separate movement corridors within the Central Asian Flyway, likely representing two distinct populations that show relatively strong connectivity between breeding and wintering areas. Bar-headed geese marked at seven locations in the Central Asian Flyway showed heaviest use at several stopover sites in the same general region of high-elevation lakes along the eastern Qinghai-Tibetan Plateau. Our analysis of data from multiple Anatidae species marked at sites throughout Asia highlighted major movement corridors across species and confirmed that the Central Asian and East Asian-Australasian Flyways were spatially distinct. Conclusions The dynamic Brownian bridge movement model improves our understanding of flyways by estimating relative use of regions in the flyway while providing detailed, quantitative information on migration timing and population connectivity including uncertainty between locations. This model effectively quantifies the relative importance of different migration corridors and stopover sites and may help prioritize specific areas in flyways for conservation of waterbird populations. Electronic supplementary material The online version of this article (doi:10.1186/s40462-015-0029-6) contains supplementary material, which is available to authorized users.

On the wings, bodies, and heads of most birds there are lice. These lice spend their whole lives on their host, with the exception of the few lice that get the opportunity to transfer from one host to another, typically when the hosts come into physical contact with each other. In shorebirds (Charadriiformes), such opportunities are unevenly distributed over the year. The hosts are spread out over vast areas in their Arctic breeding grounds during the Arctic summer, but form dense, multispecies flocks in the tropics and subtropics during the Arctic winter. During autumn and spring, when the hosts migrate between the Arctic to the tropics, they follow more or less well-defined routes, called flyways. In this thesis, the impact of this host migration pattern on the phylogeny of shorebird lice is evaluated. More specifically, two complementary hypotheses of pattern formation in the evolutionary history of shorebird lice, flyway homogenisation and flyway differentiation, are tested by phylogenetic reconstruction of the evolutionary history of two genera of lice (Lunaceps and Carduiceps) that parasitize the same group of sandpiper (Scolopacidae: Calidrinae) hosts. Flyway homogenisation is founded on the assumption that opportunities for lateral spread of lice between hosts of different species are prevalent in flyways, which will facilitate gene flow between louse populations on different host species, and prevent speciation of lice on host species that use the same stop-over points and wintering grounds. Over evolutionary time, this would cause a pattern of host species migrating along the same flyways having genetically similar or identical louse populations. Flyway differentiation is, conversely, the hypothesis that the division of a widely spread host species into discrete populations that each follow different flyways during migration will work as an isolating mechanism on the lice. If the generation time of the lice is significantly shorter than that of their hosts, this would result in a pattern where the same Holarctic-breeding host species is parasitized by genetically different louse populations in different parts of the world. Extrapolating from data published on other groups of lice, flyway homogenisation is expected to be more pronounced in wing lice (Lunaceps) than in body lice (Carduiceps) as these are topologically better placed on the host to take advantage of opportunities of lateral transfer to novel host species. Flyway differentiation is expected to be more pronounced in Carduiceps than in Lunaceps, as wing lice of vagrant hosts migrating along the “wrong” flyway would transfer to novel hosts more easily, and could prevent complete isolation between flyways. While no evidence is found in either genus for flyway differentiation, there is evidence for flyway homogenisation in Lunaceps, with three Lunaceps species occurring on multiple host species using the same flyways. Surprisingly, most Carduiceps collected across the world are genetically almost identical, and thus less isolated on their hosts than are Lunaceps. Both Lunaceps and Carduiceps show some partial evidence of a division between lice on New World hosts and those on Old World hosts. This division in echoed in a larger molecular study on the proposed louse family Rallicolidae, where several species group together according to host biogeography rather than host relationships, thus contradicting the so-called Fahrenholz’ rule that states that parasite phylogeny should come to mirror host phylogeny. In the same phylogeny, evidence is presented that the genus Quadraceps, widely distributed on most groups of shorebirds, is paraphyletic with regards to most other louse genera on shorebirds, and is in need of further study. Finally, the genus Lunaceps is revised morphologically. Six new species and one new subspecies are described, and all old species are re-described and illustrated, several for the first time. Five previously recognised species are placed as synonyms to other species, one species is transferred to the genus Quadraceps, one species is resurrected from synonymy, one species is considered a nomen dubium and three populations are placed as incerta sedis.